The ABB DR/S 4.1 KNX Choke (order code 2CDG110029R0011) is a modular DIN-rail choke used to decouple an additional KNX bus line when that line is fed from a power-supply output that has no integrated choke. Without a choke, DC supply and telegram traffic on a KNX TP line are not correctly separated — so every unchoked feed to a bus line needs a DR/S (or the supply’s built-in choke).

Typical pairing is the auxiliary 30 V DC output without choke on supplies such as SV/S30.640.5.1 or SV/S30.640.3.1. The main bus output of those supplies already includes a choke; each extra KNX line taken from the unchoked output needs its own DR/S 4.1. Do not place a second choke in series on a line that already has an integrated choke.

DR/S 4.1 is a passive component — there is no ETS application, no KNX address and no bus current rating of its own. Wire polarity and conductor sizes from the ABB connection diagram; mount the 2 MW MDRC module next to the power supply.

Key Features — Extra-Line Choke

• Line decoupling: Provides the choke required for a second (or further) KNX TP line.
• Works with dual-output SV/S units: Use on the unchoked 30 V auxiliary output only as documented by ABB.
• One choke per additional line: Repeat DR/S for each extra line fed from an unchoked output.
• 2 MW MDRC: Compact DIN-rail footprint next to the power supply.
• No commissioning software: Wire according to the connection diagram; no ETS download.

At a Glance

Specification	Detail
Product type	KNX choke, MDRC
Order code	DR/S4.1 (2CDG110029R0011)
Function	Decoupling choke for an additional KNX line
Width class	2 MW
KNX ETS application	Not applicable — passive
Typical pairing	SV/S auxiliary 30 V output without choke
Not for	Series stacking on an already choked main output

Observe polarity, conductor cross-sections and one-choke-per-additional-line rules in the ABB technical data and installation instructions under Downloads.